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采用原位电化学监测技术研究了SO42-对NiCu低合金钢在除氧NaHCO3溶液浸泡过程中腐蚀行为的影响,并利用XRD和SEM对浸泡后样品的锈层相结构和表面形貌进行了分析.结果表明,与纯NaHCO3溶液相比,SO42-的添加会在浸泡初期加速基体的腐蚀,在后期抑制保护性腐蚀产物膜的生成,促使腐蚀模式由未加入SO42-时的预钝化行为向活性溶解转变.此外,SO42-与HCO3-浓度的升高均有助于Fe6(OH)12CO3的生成.样品表面腐蚀产物最终由a-FeOOH,Fe3O4和Fe6(OH)12CO3构成,表面形貌均以均匀腐蚀为主.
The effects of SO42- on the corrosion behavior of NiCu low alloy steels in the process of oxygen-scavenging NaHCO3 solution immersion were studied by in-situ electrochemical monitoring technique. The phase structure and surface morphology of the rust layer were analyzed by XRD and SEM The results show that the addition of SO42- accelerates the matrix corrosion at the initial stage of immersion compared with the pure NaHCO3 solution and inhibits the formation of the protective corrosion film at the later stage and promotes the corrosion pattern from the pre-passivation without adding SO42- In addition, the increase of concentration of SO42- and HCO3- contributes to the formation of Fe6 (OH) 12CO3.The surface corrosion products of the samples are finally composed of a-FeOOH, Fe3O4 and Fe6 (OH) 12CO3, Mainly uniform corrosion.